Power tool and method for carrying out charge equalization between accumulators in a power tool
A power tool having a first accumulator and a second accumulator, wherein the power tool has a first power electronics system with a first inverter and a second power electronics system with a second inverter, wherein the first inverter is electrically connected to the first accumulator and the second inverter is electrically connected to the second accumulator. The first power electronics system includes a first charge equalization device while the second power electronics system includes a second charge equalization device. The charge equalization devices are configured to carry out charge equalization between the accumulators. Furthermore, the power tool includes a device for speed control. In a second aspect, the invention relates to a method for carrying out charge equalization between two accumulators in a power tool. In this case, the charge equalization is preferably carried out by different load splitting via the charge equalization devices of the power electronics systems.
1. A power tool comprising:
a first accumulator;
a second accumulator;
a first power electronics system with a first inverter;
a second power electronics system with a second inverter, wherein the first inverter is electrically connected to the first accumulator and the second inverter is electrically connected to the second accumulator;
the first power electronics system including a first charge equalizer and the second power electronics system including a second charge equalizer, the first and second charge equalizers configured to carry out charge equalization between the first and second accumulators; and
a speed controller, the speed controller connected upstream of the first and second charge equalizers;
the first and second power electronics system each having a current flow controller downstream of the first and second charge equalizers.
2. The power tool as recited in claim 1 further comprising a motor having a rotor and a stator with a first winding and a second winding.
3. The power tool as recited in claim 1 wherein the first and second inverters are configured to ascertain state data relating to the first and second accumulators and to exchange the state data via a communication connection existing between the first and second inverters.
4. The power tool as recited in claim 3 wherein the state data include current values or voltage values describing a performance of the first and second accumulators.
5. The power tool as recited in claim 3 wherein the state data are selected from at least one of a group consisting of: charge, temperature, source voltage, maximum discharge current, and optimum discharge current of the first and second accumulators.
6. The power tool as recited in claim 1 wherein the speed controller, a current controller or the first and second inverters are implemented in the form of block, trapezoidal or sinusoidal commutation.
7. The power tool as recited in claim 2 wherein the motor is a brushless motor.
8. The power tool as recited in claim 1 further comprising a battery management system or a cell management system.
9. The power tool as recited in claim 8 wherein the battery management system or the cell management system is configured to detect state data relating to the first and second accumulators.
10. A method for carrying out charge equalization between two accumulators in a power tool as recited in claim 1 , the method comprising the following steps:
a) operating the power tool, a motor of the power tool being supplied with electrical energy by the first accumulator and the second accumulator;
b) ascertaining state data relating to the first and second accumulators using the first and second power electronics systems;
c) carrying out speed control using the speed controller;
d) carrying out charge equalization between the first and second accumulators as a function of the previously ascertained state data using the first and second charge equalization devices of the first and second power electronics systems;
the first and second power electronics system each having a current flow controller downstream of the first and second charge equalizers.
11. The method as recited in claim 10 wherein the charge equalization is implemented by different load splitting.
12. A power tool comprising:
a first accumulator;
a second accumulator;
a first power electronics system with a first inverter;
a second power electronics system with a second inverter, wherein the first inverter is electrically connected to the first accumulator and the second inverter is electrically connected to the second accumulator;
the first power electronics system including a first charge equalizer and the second power electronics system including a second charge equalizer, the first and second charge equalizers configured to carry out charge equalization between the first and second accumulators; and
a speed controller, the speed controller connected upstream of the first and second charge equalizers;
wherein the first and second inverters are configured to ascertain state data relating to the first and second accumulators and to exchange the state data via a communication connection existing between the first and second inverters.
13. The power tool as recited in claim 12 wherein the state data include current values or voltage values describing a performance of the first and second accumulators.
14. The power tool as recited in claim 12 wherein the state data are selected from at least one of a group consisting of: charge, temperature, source voltage, maximum discharge current, and optimum discharge current of the first and second accumulators.